Matt Targett scored twice in the first half as Middlesbrough returned to winning ways with a 3-1 victory at Birmingham.
After three winless games, Boro earned a deserved three points at St Andrew's, inspired by a former Aston Villa player in Targett, who struck twice in the first 26 minutes.
Marvin Ducksch pulled one back early in the second half as the Blues looked to rally, but David Strelec sealed the win on the hour mark for Boro.
It sends Boro four points clear of Millwall in third with 11 games to go, while the next-nearest challengers Ipswich and Hull are six points behind. They both still have games in hand, and they meet at Portman Road on Tuesday night, live on Your Site+.
The night did not begin too comfortably for Boro, but the promotion chasers flexed their quality with the first proper opportunity of the match to open the scoring in the 13th minute.
Aidan Morris hit a diagonal ball into the path of Targett, who timed his run perfectly to get behind the defence and tuck home a composed finish beyond James Beadle.
Targett made 89 appearances for Birmingham’s arch rivals Villa, and he was quick to silence the home supporters with his celebration.
The goal completely shifted the momentum and Middlesbrough capitalised once again by doubling their advantage 13 minutes later.
Christoph Klarer lost possession in a dangerous area to Hayden Hackney and the midfielder nodded to Targett, who was on hand to expertly bury his second goal of the night.
It took just three minutes of the second period for the hosts to halve the deficit after Jay Stansfield broke the offside trap and cut the ball back for Ducksch to roll home.
All of a sudden the away side looked nervous and Brynn produced a fine save to stop Ducksch equalising.
Middlesbrough settled those nerves as they re-established their two-goal lead on the hour.
Luke Ayling provided a dangerous cross for Strelec to guide his header in off the post to earn a much-needed three points for Boro and inflicting a rare home defeat on Birmingham.
Middlesbrough's Kim Hellberg:
"It was a good win, a strong win against a very good side who had only lost once in two years at this ground. It is a difficult place to come.
"We knew they would start well with the noise of the crowd around them. We took control of the game a bit better [after the goal], then we were very good in the first half with our pressing. We created a lot of opportunities and could have scored more.
"We play in different shapes all the time but I felt like [the back three] would suit us today.
"The pressure is on every day. But we always work the same way, even when we don't get the results. That's what I'm always proud of."
Former Middlesbrough defender - and current club loan manager - Tommy Smith:
"He's a real calming influence, certainly from my point of view. I work alongside him now, which I'm very fortunate to do.
"He exudes confidence and calm, and that translates to the players.
"Those three games that Middlesbrough didn't pick up any wins in, I was never overly worried by it because the performances have still been there.
"They go to Birmingham tonight and win like that. It's not a surprise to me."
Birmingham's Chris Davies:
"I was really pleased with how we started the first half. The goal was really out of nothing.
"From there we weren't as good, and then we conceded a sloppy second. We lost our way after that and it put us in a really tough position. It rocked us, and we're not used to being in that position at home.
"We regrouped well, got the goal and it put us in a great position to come back. Then we conceded another disappointing goal from our point of view. It's a good header, but poor defending.
"It was a very difficult night for us, and we've not had too many like that at home. There are 11 games to go now, and we're going to need a lot of points to get [to the play-offs]."
